The present technology relates to a storage control device, memory system, information processing system and storage control method, and more particularly, to a storage control device, memory system, information processing system and storage control method for controlling a non-volatile memory.
Non-volatile memory (NVM) is occasionally used as an auxiliary storage device or storage in recent information processing systems. This non-volatile memory is broadly classified into a flash memory that can be accessed for large units of data and a non-volatile random access memory (NVRAM) that can be quickly and randomly accessed for small units of data. Here, a typical example of a flash memory is a NAND-type flash memory. On the other hand, ReRAM (Resistance RAM), PCRAM (Phase-Change RAM) and MRAM (Magnetoresistive RAM) are examples of non-volatile random access memories.
Errors may occur due to failure to write data properly during a write to these non-volatile memories. For example, errors often occur in a memory cell whose characteristics have deteriorated due, for example, to deterioration over time or initial defect. In general, a memory cell that has developed an error during a write is regarded as a defective cell and excluded from target cells to be written from the next write and beyond. Therefore, if the number of defective cells increases, the substantial capacity of the non-volatile memory declines. Therefore, a storage device has been proposed which performs a retry process adapted to attempt to write the same data again if a data write is not performed properly (for example, refer to Japanese Patent Laid-Open No. 2004-220068).